The present invention concerns a method for assembling a screwed crown, such as a winding crown, onto a watch case.
More particularly, the invention concerns an assembly method of this type allowing the position of a screwed crown on a watch case to be set with respect with a pointer on the face of a watch case so that a logo placed on the front of said crown can always be easily brought into a determined position or orientation after having been unscrewed.
The invention also concerns a watch case provided with a screwed crown including a logo wherein the logo is oriented in a determined manner.
The manufacture and assembly of screwed crowns onto watch cases are well known. However, the assembly methods for these crowns have an important drawback. Known assembly methods do not allow one to ensure that the crown has been brought into a determined orientation with respect to the case after having been unscrewed, which is detrimental to the aesthetic appearance of the case when a mark or logo is affixed to a face of the crown. This situation is of course unacceptable when such crowns are fitted to luxury and high quality products.
The main object of the present invention is to overcome the drawbacks of the aforementioned prior art by providing a simple and economical method for assembling a crown including a logo or a mark which systematically allows the crown to be screwed back into a determined position or orientation after having been unscrewed.
The invention therefore concerns a method for assembling a screwed crown on a watch case, characterised in that it includes the following steps:
providing a crown with an inner threading the position of which is set with respect to the logo arranged on the front face of the crown;
providing an intermediate tube including two threaded sections;
mounting said intermediate tube in a smooth through hole of the case and wedging it on an assembling jig to arranged the thread start of the tube intended to accommodate the internal screw thread of the crown in an angular position such that when the crown is screwed as far as possible onto the tube said logo is located in a determined position;
providing a nut and immobilising the tube in said angular position.
According to an advantageous feature of the invention, the manufacture of the crown with the angularly set internal screw thread includes the following steps:
providing a threaded ring;
positioning said ring using an assembling jig so as to set the position of said internal screw thread with respect to the logo or the mark borne by the face of said crown; and
immobilising said ring on said crown in said set position.
The invention also concerns a watch case including a screwed crown provided with an internal screw thread, the front face of said crown including a logo or a mark, an intermediate tube including a threaded external section intended for accommodating said internal screw thread, said intermediate tube being fixedly mounted in the case, the latter being characterised in that the position of the internal screw thread of the crown is set with respect to the logo or the mark and in that the intermediate tube is mounted in the case in order to be able to be oriented angularly with respect to the case and fixed on the case in a determined angular position.
According to an advantageous feature, on the side opposite said front face the crown includes an annular groove in which a ring provided with an internal screw thread is fixedly mounted. According to another feature, the ring is welded to the crown.
According to another feature, the intermediate tube is mounted in a smooth hole arranged in the case and is secured to the case by means of a nut.